1. Field of Invention
This invention relates to the recovery of olive oil, specifically, to an improved filter system to extract juice containing oil from olive and other fruit pastes.
2. Description of Prior Art
In the production of olive or other fruit oil the first step is to mill or grind the fruit into a paste. In the case of olives the pits are ground into the paste. The second step is to agitate and warm the paste if necessary to increase oil release. The third step is to extract the juice which includes the oil from the paste. The fourth step is to separate the oil from the juice.
This invention addresses the third step of extracting the juice containing oil from the paste. In the earliest method employed the paste was placed in a porous bag and pressed by any available means to express the juice. One of the present methods employed is to first spread the paste on specially made round mats which are then placed one on top of the other to form a stack. The stack is then placed between the stationary and moveable platens of a press and subjected to an axial force. The force exerted creates an internal pressure in the paste causing the juice to flow radially outward to the edges of the mat where it then flows down into a container provided at the base of the stack. A relatively dry residue or pomace remains on the mats.
Current mats are woven from various materials such as cord and yarn to form a semi rigid circular shape. They are available in various diameters up to about 80 centimeters, have an approximately 8-22 centimeter diameter hole in the center, and are approximately 7 millimeters thick. Due to the method of construction a center hole is required to fabricate these mats, but is not functionally necessary in the extraction process. They are relatively expensive and being foreign made are not readily available, particularly in a small size that would be suitable for use in a small homeowner or experimental press. Cleaning these mats after a seasons use is difficult because they retain a considerable amount of oil due to their thickness and construction. If not thoroughly cleaned they must either be stored in a freezer to prevent the trapped oil from going rancid, or discarded.
Paste must be applied in a controlled amount and at a distance in from the edges to prevent the paste from overflowing when pressed. Since mats of different mesh size or flow rate are not available, the amount of paste applied must be continuously changed depending on the viscosity of the paste which varies with fruit variety and ripeness. As the juice flows radially outward to the edge of the mat the length that it must flow can be as long as the radius of the mat. Due to the method of construction current mats do not have radial conduits for the juice to flow through thereby, resulting is slow, restricted flow. In the case of olives some of the juice also flows through the paste itself through small conduits formed by the crushed pits. Such a long and restricted flow is inefficient, requiring an hour or more and sometimes multiple pressings to completely extract the juice.